Using Khan doesn't mean he's rehashing an episode (or movie). The overall plot, and most of the details, were unique.

"Most", he says. Is it too much to ask for "all"?

Khan's story has already been told. I never wanted anybody to tell(yes, rehash) it again. Didn't we already have a Wrath of Khan tribute in Nemesis?

Kirk's story has already been told too. But we've been given a fresh contemporary take on a classic, iconic character who now has an alternate history to take us in directions that are different, but strangely similar.